Update sphinx extension logging

Sphinx 1.6 deprecated using the application object to perform logging
and it will be removed in the upcoming 2.0 release. This updates our
extensions to use the recommended sphinx.util.logging instead.

Change-Id: I3abce4e3c147befd0235820cb8850fe18f6dee42
Signed-off-by: Sean McGinnis <sean.mcginnis@gmail.com>

doc/ext/list_plugins.py

@@ -16,10 +16,12 @@ from docutils import nodes
 from docutils.parsers import rst
 from docutils.parsers.rst import directives
 from docutils.statemachine import ViewList
+from sphinx.util import logging
 from sphinx.util.nodes import nested_parse_with_titles
-
 from stevedore import extension
 
+LOG = logging.getLogger(__name__)
+
 
 class ListAuthPluginsDirective(rst.Directive):
     """Present a simple list of the plugins in a namespace."""
@@ -32,12 +34,8 @@ class ListAuthPluginsDirective(rst.Directive):
 
     has_content = True
 
-    @property
-    def app(self):
-        return self.state.document.settings.env.app
-
     def report_load_failure(mgr, ep, err):
-        self.app.warn(u'Failed to load %s: %s' % (ep.module_name, err))
+        LOG.warning(u'Failed to load %s: %s' % (ep.module_name, err))
 
     def display_plugin(self, ext):
         overline_style = self.options.get('overline-style', '')
@@ -89,5 +87,5 @@ class ListAuthPluginsDirective(rst.Directive):
 
 
 def setup(app):
-    app.info('loading keystoneauth1 plugins')
+    LOG.info('loading keystoneauth1 plugins')
     app.add_directive('list-auth-plugins', ListAuthPluginsDirective)